Multilayer coated abrasive element for bonding to a backing

A coated abrasive element for bonding at a surface thereof to a backing by means of a brazing or binder material comprising:

• a polycrystalline element;
• an inner layer of a refractory metal or alloy coated on at least a portion of said polycrystalline element;
• a compliant layer of a ductile metal or alloy coated on said inner layer, said compliant layer having a thickness sufficient to substantially prevent cracking of said polycrystalline element caused by the transfer of stress to said polycrystalline element during cooling after said coated abrasive element is bonded to said backing;
• and
• an outer layer of a metal or alloy coated on said compliant layer and having a melting point higher than said compliant layer, said outer layer being sufficiently thick so as to be substantially impervious to said brazing or binder material during bonding to said backing.

A coated abrasive element for bonding at a surface thereof to a backing by means of a brazing or binder material comprising:

• a polycrystalline diamond element;
• an inner layer of a carbide forming metal, said inner layer being adjacent to said polycrystalline diamond element and being sufficiently thick so as to substantially cover and seal a surface of said polycrystalline diamond element:
• a compliant layer of a ductile metal or alloy coated over said inner layer, said compliant layer being sufficiently thick so as to reduce the transfer of stress to said diamond element for preventing cracking of said diamond element during cooling after said coated abrasive element is bonded to said backing;
• and
• an outer layer of a metal or alloy coated over said compliant layer and having a melting point higher than that of said compliant layer, said outer layer being sufficiently thick so as to be substantially impervious during bonding to said binder material.

An abrasive element for bonding at a surface thereof to a backing by means of a brazing or binder material comprising:

• a polycrystalline element;
• an inner layer of a refractory metal selected from the group consisting of tungsten, molybdenum, chromium, vanadium, titanium, zirconium, rhenium, niobium, tantalum and alloys thereof, said inner layer being coated on a surface of said polycrystalline element and being sufficiently thick so as to substantially cover and seal said surface of said polycrystalline element;
• a compliant layer of a refractory metal selected from the group consisting of copper, gold, nickel, silver and alloys thereof, said compliant layer being coated on said inner layer and being sufficiently thick so as to reduce the transfer of stress to said polycrystalline element;
• and
• an outer layer of a refractory metal selected from the group consisting of tungsten, molybdenum, chromium, vanadium, titanium, zirconium, rhenium, niobium, tantalum and alloys thereof, said outer layer being sufficiently thick so as to be substantially impervious during bonding to said brazing or binder material;
• and
• at least one additional metal layer between said inner layer and said compliant layer or between said outer layer and said compliant layer, said additional metal layer consisting of a metal or metal alloy which is at least partially soluble in the materials which form the layers that are adjacent to said additional metal layer.

A method of forming a matrix backing onto a multicoated abrasive element including the steps of:

• forming a multicoated abrasive element by applying an inner metal layer to a polycrystalline diamond element, said inner metal layer consisting of a carbide forming metal;
• applying a compliant metal layer on said inner metal layer, said compliant layer consisting of a ductile metal or alloy;
• applying an outer metal layer on said compliant layer, said outer metal layer consisting of a refractory metal or alloy;
• placing said multicoated abrasive element and a matrix forming metal powder in a mold, said matrix forming metal powder being selected from a group consisting of tungsten carbide, cemented tungsten carbide, tungsten powder, iron powder, and cast tungsten carbide;
• melting and infiltrating a binder infiltrant through said matrix forming metal powder at a temperature below 1070.degree. C., said binder comprising a copper based alloy composed of about 55-60% by weight copper, about 20% by weight manganese and about 20-25% by weight of zinc.

A method of forming a matrix backing onto a multicoated abrasive element including the steps of:

• forming a multicoated abrasive element by applying an inner metal layer to a polycrystalline element, said inner layer metal being selected from the group consisting of tungsten, tantalum or molybdenum;
• applying to said inner metal layer a compliant metal layer consisting of a material selected from the group consisting of gold, copper, nickel, silver and alloys thereof;
• applying an outer metal layer on said compliant layer, said outer metal layer consisting of a metal selected from the group consisting of tungsten, tantalum, molybdenum, and alloys thereof;
• placing said multicoated abrasive element and a matrix forming metal powder in a mold, said matrix forming metal powder being selected from a group consisting of tungsten carbide, cemented tungsten carbide, tungsten powder, iron powder, and cast tungsten carbide;
• melting and infiltrating a binder infiltrant through said matrix forming metal powder at a temperature below 1070.degree. C., said binder comprising a copper based alloy composed of about 55% to 60% by weight copper, about 20% by weight manganese and about 20% to 25% by weight of zinc.

A method of forming a mosaic cutter comprising the steps of:

• placing a plurality of coated cutters into a mold assembly;
• placing a matrix powder into said mold over at least a portion of said plurality of cutters;
• and
• melting and infiltrating a binder infiltrant through said matrix powder, thereby bonding said matrix powder to said coated cutters;
• wherein said coated cutters comprise a polycrystalline diamond substrate, an inner layer of a carbide forming metal or alloy coated on at least a portion of said polycrystalline diamond, a compliant layer of a ductile metal or alloy coated on said inner layer, said compliant layer having a thickness sufficient to substantially prevent cracking of said polycrystalline diamond caused by the transfer of stress to said polycrystalline diamond during cooling after said infiltration, and an outer layer of a metal or alloy coated on said compliant layer and having a melting point higher than said compliant layer, said outer layer being sufficiently thick so as to be substantially impervious to said binder infiltrant.

A method of forming a drill bit comprising the steps of:

• brazing a coated element to a cemented tungsten carbide support;
• and
• attaching said support to a bit;
• wherein, said coated element comprises a polycrystalline diamond substrate, an inner layer of a carbide forming metal or alloy coated on at least a portion of said polycrystalline diamond, a compliant layer of a ductile metal or alloy coated on said inner layer, said compliant layer having a thickness sufficient to substantially prevent cracking of said polycrystalline diamond caused by the transfer of stress to said polycrystalline diamond during cooling after said infiltration, and an outer layer of a metal or alloy coated on said compliant layer and having a melting point higher than said compliant layer, said outer layer being sufficiently thick so as to be substantially impervious to said binder infiltrant.